[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Big Dinosaur Prints Found



    Adam Britton asks of postulated injury at the base of the tail causing
tail dragging by dinosaurs,
"Why the base?" and adds, "Most tail injuries to wild lizards and crocs that
I've seen
are normally closer to the caudal / posterior [delete as appropriate] tip,
which is weaker and easier to break. A second cause of pathology which is
not uncommon in extant reptiles occurs through developmental problems in the
embryo, and the tail is typically affected first. Injuries or developmental
problems don't have to impede movement (or ability to survive), but they may
cause the tail to be shaped abnormally."

    Interesting facts, but I didn't suggest that tail injury resulting in
dinosaur tail dragging must necessarily occur at the base of the tail.
Let's not forget that the dinosaur tail dragging I was discussing
(Kayentapus type) was that of a bipedal theropod, not a croc or lizzard.  In
theropods, the hind legs elevated the body much higher than legs of crocs
and lizzards elevate their bodies.  I proposed injury from conflict with
another theropod, and it seems rather unlikely that an attacking theropod
would lower its head (a potentially dangerous mistake with the other
theropod biting in combat) to bite the distal end of the tail.  Why not try
to bite higher up, where it would have more tactical value and be a safer
move?

    Dan Varner mentioned that Richard Swann Lull, Ph.D., D. Sc., figured
some tail drag cases in the Connecticut Valley ichnites.  A specific
reference is TRIASSIC LIFE OF THE CONNECTICUT VALLEY REVISITED, published by
the state of Connecticut, State Geological and Naturtal History Survey,
Bulletin No. 81, Hartford, 1953. (This wonderful volume, abundant with
illustrations, can sometimes be located through a good book-search engine
like bibliofind.  Anyone serious about study of ancient tracks should
acquire the volume.  There was also Bulletin No. 24, same publisher, by
Lull, but it is not as complete, yet also occassionally available.) Several
examples of dinosaur tracks with tail drags are described, including the
following:  Selenichnus falcatus, attributed to, "A small coelusaurian
dinosaur"; Hyphepus fieldi, with a remarkably sinuous tail drag and
attributed to, "A small coelusaurian dinosaur, possibly web-footed"; and the
most impressive of all, Gigandipus caudatus, the largest of the Connecticut
valley forms, and attributed to, "A carnosaurian dinosaur".

    The Gigandipius caudatus footprint is about 44 cm long (about 17
inches).  Generic characters: "Huge, bipedal forms.  Tetradactyl, hallux
incumbent, half rotated.  Foot flatly digitigrade.  No manus imprint
present.  Caudal trace sinuous and continuous."  The most striking feature
of the Gigandipus caudatus footprint, per se, is, "...the small hallux which
impresses for its entire length and therefore arises lower on the foot than
in Anchisauripus, in which only the tip of the claw touches, lies much
further to the rear, and represents a more powerful grasping talon."

    Gigandipus caudatus very closely resembles Eubrontes giganteus and is
often confused with that ichnospecies when the prominent hallux and tail
trace are not present in the specimen.

    In Lull's reporting of the dinosaur trackways with tail drags ("caudal
traces", as he calls them), there is no suggestion of him interpreting those
marks as being the result of any pathology, and I suspicion that he
considered tail dragging a perfectly normal occurrence within those
inchnospecies.  Also, there is no evidence known to me that the pioneer of
track studies in the Connecticut valley, Edward Hitchcock, considered tail
dragging an evidence of pathology, either.  Unfortunately, I am unsure how
many examples of each of the above-named caudal trace ichnite types were
available for study by Hitchcock -- an important consideration when the
question of pathology arises.

    For what it's worth,
    Ray Stanford